Vehicle Air Dam System

ABSTRACT

An air dam is made of flexible cells installed adjacent to one another so that the air dam is capable of installation in many deflecting configurations on a vehicle and can also deflect under impact. The air dam system may be capable of being deployed at higher speeds while being stowed under the frame of the truck when the truck is operating on rough road surfaces to reduce the potential for air dam damage. The air dam system can be actuated pneumatically and when deployed tends to reduce aerodynamic drag by altering the path of airflow under and/or immediately around a vehicle. Other methods of actuation such as hydraulic or mechanical components may also be used with the air dam system. Alternatively, the air dam cells may be stationary and include an inflated bladder and/or flexible sleeve mounted adjacent to one another on an air dam frame.

TECHNICAL FIELD

The invention relates generally to the field of over-the-road vehiclesand more particularly to vehicle components directed at reducing theaerodynamic drag of over-the-road vehicles.

BACKGROUND

Fuel efficiency is of increasing importance to the operation of landvehicles in light of rising fuel prices and ecological concerns. This isespecially true in the field of over-the-road highway trucks. Thesetrucks travel great distances at relatively high speeds. Any improvementthat reduces the aerodynamic drag on the truck at highway speeds canhave a significant impact on the fuel economy of the truck.

Typically, over-the-highway trucks include a number of body componentsaimed at reducing drag and improving fuel economy. For example, sometrucks have fairings installed above the roof of the cab to direct airmore smoothly over the transition between the cab and the trailer. Thedesign of hoods and fenders focuses on creating an aerodynamic surface.Another component that is often used to reduce drag is the air dam,which is a deflective shield installed between the frame of the truckand the ground. An air dam routes air around the truck's bottom smoothlyto improve aerodynamic performance. Most air dams are constructed ofrelatively rigid materials that can be cracked or damaged by uneven roadsurfaces that may be found on parking lots and surface roads. Because ofthe potential for damage, additional clearance between the air dam andthe ground may be necessary at the expense of the air dam's performanceat highway speed on smooth road surfaces.

SUMMARY

An air dam that is made of flexible cells installed adjacent to oneanother is capable of installation in many deflecting configurations ona vehicle and can also deflect under impact.

In one exemplary air dam system described herein, the air dam system iscapable of being deployed at higher speeds while being stowed under theframe of the truck when the truck is operating on rough road surfaces toreduce the potential for air dam damage. The air dam system can beactuated pneumatically and when deployed tends to reduce aerodynamicdrag by altering the path of airflow under and/or immediately around avehicle. Other methods of actuation such as hydraulic or mechanicalcomponents may also be used with the air dam system. The air dam systemmay be designed into future production vehicles or added to an existingvehicle as a retrofit device. While targeted to the “over the road”Class 8 truck market, the device is equally applicable to virtually allmodes of ground transportation.

The exemplary pneumatic air dam system consists of multiple flexiblehollow or inflated structures in various geometric forms having crosssectional shapes such as circles, ovals, rectangles, and trapezoids anda height of sufficient length to span from the truck's underside to justabove the ground. These structures are herein referred to as cells, andfor the purposes of this description each cell has a circular crosssection of approximate four inches in diameter and is approximately nineinches long. To form the air dam system, multiple cells are placedtogether with each cell's long edge abutted to the next cell's long edgeto form a continuous barrier. Each cell is made of an internalinflatable bladder and/or a flexible impact resistant sheath. Since thecell is flexible, significant impacts will cause the cell to deflect,such as when the cell males contact with debris on the paved surfaceover which the vehicle is traveling. In such an impact situation, thecell, upon removal of the deflecting force, returns to its pre-deflectedstate and position.

According to one embodiment, the cells are inflatable bladders that areselectively deployable. When the bladder is filled with air, the cellbecomes more rigid so that the cell will not deflect under the pressureof air moving at velocities typically encountered in a vehicle travelingon a paved surface. When the air dam system is not activated, thedeflated cells are lifted up toward the undercarriage of the truck suchthat the deflated cell is removed from general sight and impact. Aspring steel wire is contained in the sleeve to provide a retractingforce to lift the deflated cell when the air dam system is notactivated. The spring steel lifting force is overcome when the system isactive.

In alternative embodiments, the air dam system cells can include only aninflated bladder or a flexible sleeve. The inflated cell may or may notbe enclosed in a flexible sleeve. By removing the pneumatic actuationfeature, the need for air channels within the mounting structure iseliminated. An air dam system that includes cells that are eitherinflated bladders or flexible sleeves retains benefits such as the easeof placing the cells in a variety of configurations and the deflectionunder impact while simplifying the design.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective overview of an over-the-highway truck thatincludes an air dam system constructed to one embodiment of the presentinvention;

FIG. 2 is a side view of the truck of FIG. 1;

FIG. 3 is a view from below the truck of FIG. 1;

FIGS. 4 and 5 are cross sectional views of an air dam cell constructedin accordance with an embodiment of the present invention;

FIGS. 6 and 7 are cross sectional views of an air dam cell constructedin accordance with an alternative embodiment of the present invention;

FIG. 8 is a cut away view of an air dam cell support and mountingstructure constructed in accordance with an embodiment of the presentinvention;

FIG. 9 is a cross sectional view of the air dam cell support andmounting structure of FIG. 8;

FIG. 10 is a cross sectional view of the air dam cell support andmounting structure of FIG. 8 taken orthogonally to the view of FIG. 9;

FIG. 11 is a cross sectional view of an air darn cell constructed inaccordance with an embodiment of the present invention;

FIG. 12 is a cross sectional view of an air dam cell constructed inaccordance with an embodiment of the present invention; and

FIG. 13 is a top view of a trailer that includes an air dam constructedin accordance with an embodiment of the present invention.

DESCRIPTION

FIGS. 1, 2, and 3 provide an overall view of the air dam systeminstalled on a class 8 truck tractor 10. It is believed that installinga trailer air dam system 53 on the trailer 14 as shown in FIG. 13 willprovide additional wind resistance benefits. The illustrated air damsystem includes under-carriage and front cell banks 20, 25 that eachconsist of a row of abutting cells 30 as will be described below. Inpractice, the cells 30 are suspended from the underside of the truckframe 15 such that, for example, the four inch diameter sections areattached to a mounting structure that is fixed to the frame 15 and thenine inch lengths extend down toward the ground. When aligned in thismanner, the cells form a barrier blocking the primary flow of air underand/or immediately around the vehicle. FIG. 2 shows a side view of thecells installed on a truck with GC indicating the air gap filled by thecells when inflated. FIG. 3 shows the typical spatial placement left toright and the resultant air path blockage created by the inflation ofthe cells. Blocking the primary flow of air under the vehicle causes areduction in the drag created by air turbulence under the carriage ofthe vehicle and has the resultant effect of improving fuel efficiency.

FIG. 3 shows the typical cell locations with respect to the vehicleframe. The cells can be positioned in a front bank 25 or anunder-carriage bank 20, or around the entire periphery of the vehicle,or any combination or subsections of these locations with varying levelsof air flow restriction. The cells may also be located around the frontof a trailer, around the entire trailer, and any combination orsubsections of these locations, again, with varying levels of air flowrestriction.

FIG. 4 shows a first embodiment of an air dam cell 30 in its inflatedcondition and illustrates the basic cell components: an impact resistantsleeve 39; an inflatable bladder 37, which resides within, and isrestrained by, the sleeve; and a spring steel wire 36. FIG. 5 shows adeflated cell in its home, curled upward, position. The upward curl iscaused by the spring steel wire 36, which in its natural state is bentinto a “U” shape. The sleeve 39 has additional lengths of material inthe front and back of the cell. The extra sleeve material is permanentlysandwiched between two malleable strips 32, typically formed of metal,in the front and back of the cell diameter, 180 degrees apart. Themalleable strip 32 has mounting tabs where the malleable strip is to bemounted to the frame of the vehicle. Each malleable strip consists ofmultiple cells mounted side by side, the number of cells beingdetermined by the spatial coverage required.

The cells are made rigid pneumatically. Utilizing low pressure, lowvolume air, cells are interconnected by small diameter pneumatic tubing34. Typically, no more than four cells will be interconnected therebyminimizing the potential for complete loss of air pressure should onecell malfunction. The malleable strips are designed to be modular suchthat strips may be replaced as needed or placed individually forlocation optimization.

FIGS. 6-9 illustrate an alternative embodiment of the pneumatic air damsystem. Each cell 50 is made up of an impact resistant sleeve 53, thatcan be made of 60 durometer silicon rubber, that surrounds an inflatablebladder 55. The spring steel wire 51, or alternatively an expandablejoint, which in its natural state has a “U” shape, is inserted into achannel 54 on the sleeve 53. The spring 51 causes the cell 50 to curlupward when the bladder is not inflated as shown in FIG. 7. Each cell ispressed onto a nipple 42 that is part of a supporting rail 41 or rails(FIGS. 8-10) that is mounted to the underside of the truck in locationsin which the air dam system is to be installed. Each rail 41 holdsmultiple cells mounted side by side, the number of cells beingdetermined by the spatial coverage required. For example, in a typicalsystem the each side of the bullet shaped deflector has a 7 foot longstraight section holding about 19 cells mounted to the truck fairing(not shown) and the arcuate section mounts about another 20 cells. Oneor more mounting points on the arcuate portion of the rail are fixed tothe truck frame.

The cells are pushed onto the nipple 42 and may be locked into positionby barbs (shown as 94 in FIG. 11) or other friction enhancing featureson the nipple and may also be connected using one or more externalclamps or ties (95, 112 in FIGS. 11, 12). The cells are made rigidpneumatically by a low pressure (such as about 7 psi) low volume airsupply 61 (FIG. 8) that is connected to the rails 41, 43. Cells areinflated by pumping air through passages 45 in the nipple. It may beadvantageous to fill the cells with air that is exhausted by variouspressurized systems on truck start up.

Referring now to FIG. 9 a cross section of a portion of a rail 41 or 43is shown. The rails can be made of aluminum or fiberglass and featurecircular shaped nipples for mounting the air dam cells. A number ofnon-intersecting interior air passages 61, 63, 65 are made in the rail.Each passage supplies air to a finite number of nipples 50, such as tennipples. The passages are independent from each other to minimize thepotential for complete loss of air pressure should one cell malfunction.The rails are designed to be modular such that they may be placedindividually for location optimization. Each rail and its interior airpassages are in communication with the pressurized air supply 61. FIG. 9shows the passageways arranged vertically, in another embodiment shownin FIG. 10, there are four interior passageways 71, 73, 75, 77equidistantly aligned side to side of the rail 41′. None of thepassageways is located along the centerline of the rail, as this iswhere the nipples are mounted to the rail. Each of the four passagewaysbegins where the rail is closest to the air supply such as at the frontof the bullet shape as shown in FIG. 9. The passageways 71, 73, 75, 77have varying lengths and have holes that serve as an air conduit to anipple 42. The holes start at the termination end of each rail. Eachpassageway has conduits for supplying ten nipples as shown in FIG. 10.

FIGS. 11 and 12 show alternative air dam cell constructions. In FIG. 11a inflated bladder 97 makes up the air dam cell 90. The bladder issealed to a nipple 93 on a mounting rail 92 that does not include airchannels. The bladder retains air present in the bladder duringinstallation due to the clamping force of a clamp 95 that holds it tothe rail. In this embodiment, the bladder is flexible enough to deflectunder impact and is easily replaceable. FIG. 12 shows yet anotherembodiment in which an air dam cell 110 is made up of a flexible sleeve117 held to a mounting rail 113 with a clamp 114. Similarly, theflexible sleeve can deflect under impact while providing sufficient winddeflection when placed adjacent other sleeves in the air dam system.

As can be seen from the foregoing description, an air dam made up offlexible cells that can be moved into and out of position can provideaerodynamic benefits to a vehicle as well as an air dam system withimproved impact resistance. The location and shape of the installationon the vehicle in front and under-carriage banks allows for the air damto be installed around the entire periphery of the vehicle including thetrailer. The air dam system has the additional benefit of being lessvisually intrusive to the design of the vehicle.

1. For use with a land vehicle, an air dam comprising a plurality offlexible deflector cells disposed adjacent to one another on an air damframe that is mounted to an underside of the land vehicle, wherein thecells project from the underside of the vehicle into a space between theunderside of the vehicle and the ground.
 2. The air dam of claim 1wherein each deflector cell can assume a stowed position and a deployedposition; wherein when the cells are in the deployed position theyproject from the underside of the vehicle to form the air deflecting airdam, forming a barrier covering a substantial portion of the groundclearance between the land vehicle and the ground.
 3. The air dam ofclaim 2 comprising an actuator that selectively actuates the pluralityof deflector cells between the stowed position and deployed position. 4.The air dam of claim 1 wherein each deflector cell is generallycylindrically shaped.
 5. (canceled)
 6. The air dam of claim 4 whereineach of said generally cylindrically shaped deflector cells include aninternal bladder.
 7. The air dam of claim 4 wherein each of saidgenerally cylindrically shaped deflector cells is made from impactresistant elastomeric material.
 8. The air dam of claim 1 wherein theair dam frame includes nipples onto which the plurality of flexibledeflector cells are press fit.
 9. The air dam of claim 7 wherein saidimpact resistant elastomeric material is silicon rubber.
 10. The air damof claim 9 wherein the durometer of the silicon rubber is substantiallyequal to
 60. 11. The air dam of claim 8 wherein the nipples includesnipples that are adjacent to one another.
 12. The air dam of claim 8wherein an outer periphery of each nipple includes one or more barbs forengaging an inner surface of the flexible deflector cells.
 13. The airdam of claim 1 comprising one or more air dam frames, each supporting atleast one of said plurality of flexible deflector cells.
 14. The air damof claim 13 wherein at least one of the one or more air dam framesextends laterally across a front of the vehicle.
 15. The air dam ofclaim 13 wherein at least one of the one or more air dam frames isdisposed on a bottom surface of the vehicle and has a generally ogivalshape having a sharpness in the approximate range of 0.5-3.5 thatoriginates at a front portion of the vehicle and radiates toward a rearportion of the vehicle such that the deflector cells route wind thatencounters the vehicle between front and rear wheels of the vehicle. 16.The air dam of claim 13 wherein at least one of the one or more air damframes is disposed on a bottom surface of a trailer carried by thevehicle and wherein the air dam has a generally ogival shape having asharpness in the approximate range of 0.5-3.5 that originates at amiddle portion of the trailer and radiates toward a rear portion of thetrailer such that the deflector cells route wind that encounters thewheels and wheel assemblies of the trailer.
 17. The air dam of claim 13wherein at least one of the one or more air dam frames is disposed on abottom surface of a trailer carried by the vehicle and wherein the airdam has a generally ogival shape having a sharpness in the approximaterange of 0.5-3.5 that originates at a rear portion of the trailer andradiates toward a front portion of the trailer such that the deflectorcells route wind that encounters the trailer aft of the rear wheels ofthe trailer.
 18. (canceled)
 19. The air dam of claim 8 wherein theplurality of flexible deflector cells are connected to a respectivenipple of said nipples on the air dam frame with a circular clamp. 19.(canceled)
 20. (canceled)
 22. A method for deflecting air encountered bya land vehicle having a frame suspended above the ground by a pluralityof wheels, the method comprising suspending a bank of adjacent flexibleair dam cells between the vehicle frame and the ground.
 23. The methodof claim 22 wherein the flexible air dam cells comprise a pluralitygenerally cylindrical impact resistant elastomeric cells.
 24. The methodof claim 23 wherein said impact resistant elastomeric cells are madefrom a silicon rubber having a durometer substantially equal to
 60. 25.The method of claim 22 wherein the step of suspending a bank of adjacentflexible air dam cells between the vehicle frame and ground furthercomprises mounting the air dam cells on a bottom surface of a trailercarried by the vehicle and wherein the air dam has a generally ogivalshape having a sharpness in the approximate range of 0.5-3.5 thatoriginates at a middle portion of the trailer and radiates toward a rearportion of the trailer such that the deflector cells route wind thatencounters the wheels and wheel assemblies of the trailer.
 26. A systemfor reducing aerodynamic drag of a motorized or non-motorized wheeledvehicle, the system comprising: a mounting fixture being supported to anunderside of a vehicle frame, the mounting fixture having a plurality ofnipples projecting from the mounting fixture toward the ground; and anarcuately-shaped resiliently deflectable air barrier assembly comprisinga plurality of independently flexible cells that extend from theunderside of the wheeled vehicle to cover a substantial portion of theground clearance between the underside of the wheeled vehicle and theground, each of the plurality of flexible cells being independentlysecured to a respective nipple of said plurality of nipples projectingfrom the mounting fixture.
 27. The system of claim 26 wherein each ofthe flexible cells comprise an impact resistant elastomeric cylinderhaving first and second ends said first end having an opening forreceiving and attaching to said respective nipple and said second endextending from said first end to the ground.
 28. The system of claim 26wherein the mounting fixture is disposed on a bottom surface of atrailer carried by the vehicle and wherein the air barrier has agenerally ogival shape having a sharpness in the approximate range of0.5-3.5 that originates at a middle portion of the trailer and radiatestoward a rear portion of the trailer such that the deflector cells routewind that encounters the wheels and wheel assemblies of the trailer.